uTalk – SIP Dialer

uDial allows you to use Android phone to make calls over over a 3G network or WiFi LAN Data Connection with almost any SIP provider.

The calls are crystal clear and integrates into your phone, eliminating the need for a separate phone book. You simply use your Android contacts in the same way as if you were making a call over a cellular network.

It allows Android users to completely untangle themselves from mobile minutes and rely on a purely VoIP solution tied to their Enterprise Desktop.
It’s really an amazing application that is stable and simple to use, with the potential to save you plenty of money.
Use your Android phone to obtain uDial from the Market.